Rotary piston compressor

ABSTRACT

A circular piston compressor arranged as compressor in the closed circuit of a medium to which a limited quantity of lubricant is added and partially dissolved therein to lubricate the compressor. The compressor includes a stationary housing with trochoidal inner boundary, an eccentric shaft, and a rotary piston mounted on the eccentric of the eccentric shaft so that the axial centerline of the piston describes a circular path during rotation thereof. A cover is present on the drive side of the housing. A suction line of the compressor is arranged on the side of the housing opposed to the drive side so that at least a portion of the oil-mist permeated intake gas is directed substantially perpendicularly at the inside of the drive side housing cover. An end wall opposing the housing cover, and working chambers are present as an end intake port and a seal between the shaft and the housing cover. An annular chamber is arranged between the housing cover and the opposing end wall and bounding the working chambers so that the intake gas is deflected in the annular chamber at right angles in the direction of rotation of the piston toward the end intake port of the working chambers thus also traversing the region in which the shaft seal is installed.

nite States Luck ROTARY PIs'roN connsson Inventor: Friedrich Luck, Berlin, Germany Assignees: Borsig Gmbll, Berlin-Tegel;

Gmbl-l, Lindau, Germany Jan. 14, 1971 Wankel Filed:

Appl. No.:

Foreign Application Priority Data Jan; 19, 1970 US. Cl .;..41 8/54, 418/100, 418/102 References Cited UNITED STATES PATENTS Germany ..P 20 02 075.1

' Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik Attorney-Kane, Dalsimer, Kane, Sullivan [57] ABSTRACT A circular piston compressor arranged as compressor in the closed circuit of a medium to which a limited quantity of lubricant is added and partially dissolved therein to lubricate the compressor. The compressor includes a stationary housing with trochoidal inner boundary, an eccentric shaft, and a rotary piston mounted on the eccentric of the eccentric shaft so that the axial centerline of the piston describes a circular path during rotation thereof. A cover is present on the drive side of s the housing. A suction line of the compressor is arranged on the side of the housing opposed to the drive side so that at leasta portion of the oil-mist permeated intake gas is directed substantially perpendicularly at the inside of the drive side housing cover. An end wall opposing the housing cover, and working chambers are present as an end intake port and a seal between the shaft and the housing cover. An annular chamber is arranged between the housing cover and the opposing end wall and bounding the working chambers so that the intake gas is deflected in-the annular chamber at right angles in the direction of rotation of the piston toward the end intake port of the working chambers thus also traversing the region in which the shaft seal is installed.

3 Claims, 3 Drawing Figures PATENTEBAPR 18 m2 3,656,875

sum 2 [IF 2 ROTARY PISTON COMPRESSOR The invention involves a rotary piston compressor having a trochoidal internal boundary of its stationary housing. A rotary piston is mounted on the eccentric of an eccentric shaft and describes a circular path with its axial centerline in the course of its rotary motion. The combination is arranged as a compressor in the closed circuit of a medium. A limited quantity of lubricant is added to and partially dissolved in the medium to lubricate the compressor. An example of this type of compressor would be a small refrigerator compressor operated with Frigen.

Rotary piston compressors of this type have not been previously utilized in the form of circular piston machines. The rotary piston typehas not previously gained any importance in practice, and has proved unsuitable as a small compressor because of its bulk and comparatively complicated construction. First and foremost, such a machine presents difficulties in that the lubricant is dissolved by the refrigerant more or less depending on temperature and pressure, and only a residue in mist or droplet form is utilized for lubrication. If the lubricant totally mingles with the medium, the machine may temporarily run dry as a result.

Especially the seal on the drive shaft is endangered by failure of lubricant supply. Not only the packing itself may suffer damage, but losses of medium may occur as well.

An object of the invention is to minimize and if possible entirely avoid any interruption of lubricant supply such as willoccur chiefly when starting. A further object is to achieve a cooling of the compression side and of the pressure side control member by the incoming medium.

This object is accomplished by arranging the suction line of the compressor on the side of the housing opposed to the drive side so that the oil-mist'permeated intake gas or a portion thereof is directed substantially perpendicularly at the inside of the drive-side housing cover. Furthermore, an annular space is arranged between the housing cover and the end wall facing it and bounding the working chambers. In the annular space, the intake gas is deflected at right angles in the direction of rotation of the rotor towards the end intake port of the working chambers, thus also traversing the region in which the shaft seal is installed. The oil droplets, of higher specific gravity, present in the medium will precipitate in part on the inside of the cover and reach the seal with the aid of the gas flow. Hence, lubricant supply to the shaft bearing will be resumed without delay as soon as more liquid oil is carried out of the compressor, or even mere remnants of oil caught on the walls of the suction line or of the drive-side housing cover are entrained by the intake gas.

The quantity of lubricant supplied to the seal can be increased by providing catch or guide grooves for the impinging oil droplets on the inside of the drive-side housing cover. Ini tially, these grooves will run more or less along the gas flow prevailing inside the annular space between the drive-side housing cover and the housing end wall facing it and then secondly turn off towards the shaft seal. In this manner, a minimum of the oil precipitated on the wall will flow past the seal. The enlargement of the wall surface opposed to the intake line because of the grooves will also favor an intensification of oiling.

The intake line, passing axially through the entire machine beside the outlet ports, will act to cool the housing on the compression side. The cooling effect can be increased, without interfering with processes of flow between intake line and end intake ports of the working chambers, by means of axially directed openings in the compression region of the housing parts. Portions of the intake gases circulating in the cavities of the housing cover will pass through these openings at differentially low temperature depending on fiow volume and pressure, from one cover chamber to the other. At the same time, this brings about some equalization of pressure, or a more uniform approach flow to the intake ports.

An embodiment of the invention, a 1:2-geared single-disc compressor of trochoid type, with intake ports at both ends, is

represented by way of example in the drawing and will be more fully described below.

FIG. 1 shows a longitudinal section of the compressor;

FIG. 2 shows a cross section at the line "-11;

FIG. 3 shows a top view of the interior of the drive side housing cover at the line Ill-III.

Referring to FIGS. 1 and 2, the compressor consists of a housing 1 with trochoidal inner boundary 2, containing a pressure valve of any common type as pressure control member 3. The end walls 4 and S bind working chambers 6 and 7 in axial direction, and each has an inlet port 8 and 9. In these end walls is mounted an eccentric shaft 10 on roller bearings 11 and 12 on the eccentric 13 of which the rotary piston 14 is arranged. The rotary piston has an internal gear 15 meshing with a pinion 16 fixed to the end wall 4. Counterweights 17 balance the eccentric masses of the shaft.

The compressor is closed off at the ends by housing covers 18 and 19. Cover 18 bears the intake connection 20, while the slip ring packing 21 sealing the shaft is arranged in cover 19.

The passage 22 adjoining the intake connection 20 and arranged directly beside the pressure valve 3 passes in axial direction through housing 1 and end walls 4 and 5. The suction gas passing through it is deflected in the cavity of housing cover 19 at right angles in the direction of rotation of piston 14 towards intake port 9 (see FIG. 3), while entrained mist droplets, owing to their greater mass inertia, precipitate on the inside of cover 19. The gas flowing to the intake port 9 will also reach the region of the shaft seal 21, and its boundary layers will deliver a greater or smaller portion of the precipitated oil to the point of lubrication of the seal.

The rate of precipitation of the oil and its supply to the seal are improved by the catch grooves 23 represented in FIGS. 1 and 3. These grooves at first run more or less in the direction of the gas flow indicated by arrow 24, and then turn 0E more or less sharply towards the seal. Since the suction passage 22 and intake port 9 are located in front of the section plane III- III, they are shown in dot-dash lines.

The arrangement of the suction passage in the neighborhood of the pressure valve effects a cooling of the housing on the hot compressor side and diminishes the hazard of leakage due to distortion of particular housing parts. Additional cooling effect can be obtained with more axial openings 25 in the compression region. These openings through housing 1 and end walls 4 and 5 connect the cavities of housing covers 18 and 19 so that unequal flows of gas circulating in the cavities will allow portions to pass over from one cover cavity to the other.

The invention extends to the case where the compressor described is a multi-disc machine, or where more than one compression stage ofthe type according to the invention are provided.

1 claim:

1. A circular piston compressor arranged as compressor in the closed circuit of a medium to which a limited quantity of lubricant is added and partially dissolved therein to lubricate the compressor comprising: a stationary housing with trochoidal inner boundary, an eccentric shaft, a rotary piston mounted on the eccentric of the eccentric shaft and describing a circular path with its axial centerline during the rotary motion thereof, a cover on the drive side of said housing, a suction line of the compressor arranged on the side of the housing opposed to the drive side so that at least a portion of the oilmist permeated intake gas is directed substantially perpendicularly at the inside of the drive side housing cover, an end wall opposing said housing cover, working chambers having an end intake port through said end wall, a seal between said shaft and said housing cover, and an annular chamber arranged between said housing cover and the opposing end wall and bounding the working chambers so that the intake gas is deflected in said annular chamber at right angles in the direction of rotation of the piston toward the end intake port of the working chambers thus also traversing the region in which the shaft seal is installed.

Aqua

wherein working chamber end walls are provided with additional axially traversing openings in the compression region in the housing connecting the cavities of the two housing covers with each other. 

1. A circular piston compressor arranged as compressor in the closed circuit of a medium to which a limited quantity of lubricant is added and partially dissolved therein to lubricate the compressor comprising: a stationary housing with trochoidal inner boundary, an eccentric shaft, a rotary piston mounted on the eccentric of the eccentric shaft and describing a circular path with its axial centerline during the rotary motion thereof, a cover on the drive side of said housing, a suction line of the compressor arranged on the side of the housing opposed to the drive side so that at least a portion of the oil-mist permeated intake gas is directed substantially perpendicularly at the inside of the drive side housing cover, an end wall opposing said housing cover, working chambers having an end intake port through said end wall, a seal between said shaft and said housing cover, and an annular chamber arranged between said housing cover and the opposing end wall and bounding the working chambers so that the intake gas is deflected in said annular chamber at right angles in the direction of rotation of the piston toward the end intake port of the working chambers thus also traversing the region in which the shaft seal is installed.
 2. Circular piston compressor in accordance with claim 1 wherein catch and guide grooves are provided on the inside of the drive-side housing cover for the impinging oil droplets, which first run more or less in the direction of the flow of gas and are then deflected toward the shaft seal.
 3. Circular piston compressor in accordance with claim 2 wherein working chamber end walls are provided with additional axially traversing openings in the compression region in the housing connecting the cavities of the two housing covers with each other. 